Conifer metabolite pisiferic acid restores activity in human Kv1.2 potassium channels carrying pathogenic sequence variants.

Sequence variants in KCNA2, the gene encoding voltage-gated potassium channel Kv1.2, cause epilepsy, delayed cognitive development, and movement disorders. Drugs that directly correct mutant Kv1.2 function are lacking. Kv1.2 downregulation is also implicated in pain and amyotrophic lateral sclerosis (ALS). We recently found that the abietane diterpenoid pisiferic acid (PA) from conifer Chamaecyparis pisifera beneficially restores activity in pathogenic loss-of-function (LOF)-variant Kv1.1 channels. Here, using cellular electrophysiology, we classified 19 human Kv1.2 gene variants (pathogenic or of unknown significance) into LOF, gain of function (GOF), or mixed LOF/GOF. By hyperpolarizing their voltage dependence of activation, PA improved function in 13/13 LOF and 1/1 LOF/GOF pathogenic Kv1.2 variants tested, using cRNA ratios representative of autosomal dominant KCNA2 disorders. In silico docking, mutagenesis, and electrophysiology identified a PA binding site in the Kv1.2 voltage sensor. Given its in vitro efficacy and low preclinical toxicity, PA is a promising lead compound for Kv1.2 LOF disorders.